Dyeing with sulfur dyes



United States Patent 3,113,824 DYEING WITH SULFUR DYES Christoph Kohl, Frankfurt am Main, and Karl Schlitz, Hubert Poppa, and Erwin Kriische, Frankfurt am Main, Feehenheim, Germany, assignors to Cassella Farbwerire Mainkur Aktiengesellschaft, Frankfurt am Main, Fechenheim, Germany, a company of Germany No Drawing. Filed Feb. 24, 1960, Ser. No. 10,563 (Ilaims priority, application Germany Feb. 28, 1959 6 Claims. (Cl. 837) The present invention relates to a dyeing process. More particularly, the present invention relates to a new process for dyeing cellulose materials, such as native and re enerated cellulose, with sulfur dyes in the form of their water-soluble thiosulfonic acids together with alkali metal hydrogensulfides or s-ulfhydrates as reducing agents.

It is known that the commercial water-insoluble sulfur dyes are usually vatted with sodium sulfide, then brought from the strongly alkaline solutions onto the cellulose fiber in the form of their leuco compounds and finally oxidized on the fiber to for-m an insoluble dye. Sodium sulfide is preferably used because it is a cheap reducing agent and it also guarantees in practice a good solubility of all of the sulfur dyes. The application of sodium sulfide, however, involves a number of disadvantages which are due to the great alkalinity of the dye liquors containing same. Thus, it is known, for instance, that such dye-liquors affect unfavonably the softness and the feel of the dyed material. This concerns especially the regenerated cellulose. (As, moreover, this fiber swells strongly during the dyeing process in alkaline dye liquors, a long and repeated rinsing becomes necessary afterwards, in order to remove completely the adhering dye liquor and the non-fixed dyestuff particles. Furthermore, difficulties arise frequently when unwinding the dyed bobbins because the fiber material to be dyed is liable to become sticky due to its strong swelling during the dyeing process.

For these reasons, efforts have been made for a long time to find a reducing agent of a reduced alkalinity which might be suited for the dyeing with sulfur dyes. Thus, a formaldehyde sodium sul-foxylate was recommended to be used in soda-alkaline solution for the purpose mentioned above. But quite apart from the fact that this reducing agent is much more expensive than sodium sulfide, it fails in many cases because of the inadequate solubility of numerous sulfur dyes in baths containing soda and formaldehyde sodium sulfoxylate. Furthermore, when working with formaldehyde sodium sulfoxylate, difficulties arise with regard to the reproducibility of shades due to over-reduction of the used dyes.

Attempts have also been made to use sodium hydrogensulfide or sulihydrate (Neil-IS) instead of sodium sulfide (Na s), which is as cheap as sodium sulfide when dyeing with sulfur dyes, because of its comparatively low alkalinity. However, it turned out that only a small fraction of the commercial water-insoluble sulfur dyes are sufi'iciently soluble in sodium sulfhydrate. In the majority of cases, undesirable precipitates of the insoluble dye are formed in the dye liquors containing sodium sulfhydrate. These precipitates lead to useless dyeings. Therefore, sodium sulfhydrate could not gain ground, especially since commercial dyeing operations :are carried out generally with mixtures of two or more different sulfur dyes and since sodium sulfhydrate provides only a few possibilities of combination because of its narrow and limited applicability.

It has now been found that the water-soluble thiosulfonic acids of sulfur dyes which may be obtained for instance according to the process described in German Patents No. 88,392 and 91,720 and which have hitherto been used successfully in dyeing operations with sodium sulfide, can be excellently dyed with :allcali-metal sulfhy- 3,113,824 Patented Dec. 10, 1963 drates as reducing agents, such as sodium sulfhydrate, possibly by addition of soda.

This result could not be foreseen, for on the one hand there was the possibility that the alkalinity of the sodium sulfhydrate would not suffice to split off the water-solubilizing thiosulfonic acid residues and that thus a fixation of the dye-stuff in its water-insoluble form could not take place. On the other hand, it was to 'be feared that even if the thiosulfonic acid residues had been split off, the same unfavorable conditions would appear, as it is the case when using water-insoluble sulfur dyes in a bath of sodium sulfhydrate, i.e., that the undesired precipitation of undissolved dye would occur Within (the dye liquor.

It is surpnising that the disadvantages mentioned above do not occur in the process of the present invention. It gives therefore, the possibility to use the water-soluble sulfur dye derivatives which yield very level dyeings and which are therefore already preferably employed in a simple dyeing method that guarantees the optimum save in the treatment of the material to be dyed.

The following Examples of the method of the present invention are given as illustrative only, the parts being by weight and all temperatures in degrees centigrade, the invention, however, not being limited to the specific details of the examples. References to C01. Index numbers :refer to the Colour Index of the Society of Dyers and Colourists," Second Edition, published by the said society at London in 1958.

Example 1 grams of the thiosulfonic acid which has been prepared from Immedialbraun BR (Col. Index, vol. 3, p. 3449, No. 53,270) according to the process described in German Patent No. 91,720, aredissolvcd in water by short boiling and then this dye solution is diluted up to 20 liters. After addition of 120 cc. of a 22% sodium sulfhydrate solution and 400 gnams calcined Glaubers salt, 1 kg. spun viscose rayon is dyed in this solution during 1 hour at a temperature of 80-90, subsequently rinsed and oxidized. The dyeing thus obtained corresponds in its depth of color and in its shade to the dyeing obtained by using sodium sulfide as reducing agent. The dyed material possesses an excellent feel.

Example 2 50 guams of the thiosulfonic acid which has been prepared from Immedialbordo B (Col. Index, vol. 3, p. 3458, No. 5 3,721) according to the process described in Ger-man Patent No. 91,720, are dissolved in water by short boiling and the dyestuff solution is diluted up to 20 liters. After addition of 60 cc. of a 22% solution of sodium sul-fhydrate and 200 grams calcined Glaubeis salt 1 kg. of spun viscose rayon is dyed at 5060 during 1 hour, then rinsed and oxidized. The dyeing is about 10% more intense than that which may be obtained with the same quantity of dye when using sodium sulfide. Their shades are identical. The material thus dyed has a full and soft feel.

Example 3 grams of the thiosulfonic acid which has been prepared from lmrnedialechtbraun GGL (Col. Index, vol. 3, p. 3451, No. 53,327) according to the process described in German Patent No. 91,720 are dissolved in water by short boiling and the :dye solution diluted up to 20* liters. After addition of 80 grams calcined soda, 200 cc. of a 22% solution of sodium sulfhydrate and 400 g. calcined Glaubers salt 1 kg. cotton is dyed in this solution at 80-90 during 1 hour, then rinsed and oxidized. The dyeing is as intense as that which is obtained in a sodium sulfide bath on analogous conditions. However, the cotton dyed according to the present invention has a remarkably softer feel than the material dyed from the sodium sulfide bath.

It will be understood that this invention is susceptible to further modification :and, accordingly, it is desired to comprehend such modifications Within this invention as may fiall the scope of the appended claims.

We therefore, particularly point :out and distinctly claim as our invention:

1. A process for dyeing a icel'l ul osic material with a water-soluble th-iosulfonic acid of a sulfur dye by treating the material to be dyed at an elevated temperature with a dye bath consisting essentially of the Water-soluble thiosulfonic acid of the sulfur dye, an alk-ali metal sulfhydnate as a reducing agent, and Water, and finishing the dyed material by rinsing, oxidizing and finally rinsing.

2. A process for dyeing a iczellulosic material with a water-soluble thiosulfionic acid of a sulfur dye by treating the material to be dyed at an elevated temperature With a dye bath consisting essentially of the Water-soluble thiosul-fonic acid of the sulfiur dye, sodium sulfhydrate as a reducing agent, and water, and finishing the dyed material by minsiing, oxidizing and finally rinsing.

3. A cellulose material dyed with a sulfur dye by treating the material to be dyed at an elevated temperature 2 with a dye bath consisting essentially of [the Water-soluble thiosulfionic acid of the sulfur dye, alkali-metal sulthydr-ate as a reducing agent, and Water, and finishing the dyed material by rinsing, oxidizing :and finally rinsing.

4. A dye bath consisting essentially of a Water-soluble thiosulfonic acid of :a sulfur dye, an alkali-metal sulfhydrate, and Water.

5. A dye bath consisting essentially of a Water-soluble thiosulfonic acid of a sulfur dye, an alkali-metal sulthydrate, soda, and Water.

6. A dye bath consisting essentially of a Water-soluble thiosulfonic acid of a sulfur dye, sodium sulfhydrate, soda, and Water.

References Cited in the file of this patent UNITED STATES PATENTS 2,091,417 Schick et a1 Aug. 31, 1937 FOREIGN PATENTS 12,327 Great Britain 1901 88,392 Germany Aug. 26, 1896 91,720 Germany March 29, 1897 

1. A PROCESS FOR DYEING A CELLULOSIC MATERIAL WITH A WATER-SOLUBLE THIOSULFONIC ACID OF A SULFUR DYE BY TREATING THE MATERIAL TO BE DYED AT AN ELEVATED TEMPERATURE WITH A DYE BATH CONSISTING ESSENTIALLY OF THE WATER-SOLUBLE THIOSULFONIC ACID OF THE SULFUR DYE, AN ALKALI-METAL SULFHYDRATE AS A REDUCING AGENT, AND WATER, AND FINISHING THE DYED MATERIAL BY RINSING, OXIDIZING AND FINALLY RINSING. 